1. Field of the Invention
The present invention relates to a suspension device for use in a crawler vehicle which has front steerable wheels with tires and rear drive wheels with crawler belts trained therearound.
2. Description of the Prior Art
Japanese laid-open utility model publication No. 3-129580 discloses a suspension device for use in a crawler vehicle having crawler belts trained around rear drive wheels.
Specifically, the disclosed suspension device has a pair of swing beams each swingable about a longitudinally central portion thereof and attached to a rear vehicle body portion through a suspension. An idle wheel with a tire and a drive wheel with a tire are rotatably mounted on respective front and rear end portions of each of the swing beams. A crawler belt is trained around the idle wheel and the drive wheel. Front wheels with tires are rotatably mounted on a front vehicle body portion. The crawler vehicle with the disclosed suspension device is capable of running over both paved roads and rough terrain.
Generally, for a vehicle with four wheels, i.e., two front wheels and two rear wheels, to be capable of running straight stably at a high speed, the distance between the front wheels and the rear wheels should preferably be as large as possible. This requirement applies also to crawler vehicles of the type described above. On the crawler vehicles, the distance between the axis about which the front wheels are rotatable and the axis about which the swing beams are swingable should be as large as possible.
Crawler vehicles should also be highly maneuverable and propellable on soft terrain such as muddy or snowy roads. Such a requirement can be met when the crawler belt portions under the idle wheels ride over the soft terrain and the crawler belt portions under the drive wheels compact the soft terrain for greater propulsive forces.